1. Field of the Invention
This invention relates to an apparatus for creating a visual display and more particularly to an apparatus for displaying two-channel audio input signals in a three-color visual pattern.
2. Information Disclosure Statement
Many different systems have been invented for the visual display of sound, particularly where the sound is music. The appeal of the resulting creation is generally enhanced if the visual display is created in color, which generally requires at least three distinct colors. A rudimentary example of this is the colored stage lights popularly used by stage musicians and controlled by foot switches or the like. An early example of a color interpretation system designed primarily for the interpretation of music is illustrated in U.S. Pat. No. 2,804,500 issued to Giacoletto on Aug. 27, 1957. Although it makes use of a three-color cathode ray tube, it essentially discloses only a single audio input separated into three frequency bands by a high pass filter, a low pass filter and a band pass filter, the outputs of which are used to drive directly the three control grids of a color cathode ray tube (CRT) employing deflection circuitry of more conventional means. In an alternative embodiment, three monochrome cathode ray tubes of different colors are driven separately in the manner disclosed by Giacoletto and the results combined optically.
A much more involved visual display system is disclosed by Yoshiharu Mita in U.S. Pat. No. 2,910,681 issued Oct. 27, 1959. This patent stresses manual control of input frequencies to each CRT deflection circuit to create what amounts to an electronic paint brush for an artist. A monochrome CRT is envisioned in this system, and provision is made to augment the manual input with musical input in a limited fashion.
A novel color display apparatus is disclosed by Shank in U.S. Pat. No. 3,163,077 issued Dec. 29, 1964 which involves merely the illumination of incandescent lamps or the like corresponding to musical signals filtered in three separate frequency bands from an audio input signal. Although frequency separation into three distinct channels for a three-color display is disclosed in the Shank patent, the system is strictly limited to what might be termed a three-channel color driver system very similar to a portion of the color driver system disclosed in the Giacoletto patent discussed above. In particular, the Shank patent is completely devoid of any attempt at pattern generation.
U.S. Pat. No. 3,723,652 issued Mar. 27, 1973, to Alles et al. discloses a novel audio-video interface network which accepts audio signals as an input and generates an rf output capable of reception by a standard, unaltered color television receiver. Direct control of the pattern is not attempted in this system however, and the invention also injects additional information on top of the audio input information by virtue of a self-contained pattern generator. It has the advantage, however, of being able to operate with a color television receiver which has not been altered in any way.
Even spoken words may be displayed as color on a television screen through devices such as disclosed in the patent issued to Esser as U.S. Pat. No. 4,378,466 on Mar. 29, 1983. Esser discloses a "visible speech" technique which is useful for persons who are hearing impaired and cannot otherwise sense audio information. Relatively sophisticated triangular filters are involved in this disclosure, but the invention merely relates to the pure translation of intelligence from one form into another for the purpose of communication. No attempt is made at control of the pattern, and no attempt is made to enhance the entertainment value by enhancing the appearance of the visual display.
A variety of other systems are known in the art which have less pertinence to the instant invention. Among these is U.S. Pat. No. 4,205,585 issued to Hornick on June 3, 1980, which discloses an audiovisual conversion system involving a light source such as a laser, the beam of which is deflected by a reflector mounted on a membrane displaced by the audio signal. U.S. Pat. No. 4,384,286 issued to DiToro on May 17, 1983, discloses a high speed graphics display processor. Synthesis of interferograms is disclosed in the Dec. 9, 1980, U.S. Pat. No. 4,238,827 issued to Geary et al. An automatic drawing device for use with a digital computer is disclosed in the patent issued to Bezrodny, U.S. Pat. No. 3,675,231 issued July 4, 1972. U.S. Pat. No. 3,662,374 issued May 9, 1972, to Harrison III, et al. discloses a system for the automatic generation of a visual mouth display in response to sound. Contrasting color display in a cathode ray tube is generally disclosed by the patent issued to Strohmeyer, U.S. Pat. No. 3,668,686 issued June 6, 1972. U.S. Pat. No. 3,476,974 to Turnage, Jr., et al. issued Nov. 4, 1969, discloses digital control of visual display of elliptical patterns.
None of the above-described systems provide a satisfactory combination of both pattern control and color control as is achieved in the invention claimed herein. Although different means of pattern control have been employed as discussed briefly above, no prior method provides means of completely filling the viewing screen with a visual pattern regardless of the type of audio input. Furthermore, the techniques previously used for controlling color are generally of the direct-drive type which can result in a total loss of color in each channel during very quiet passages of the input audio, as well as color saturation in each individual channel when the input audio is at a high level. Even where some degree of automatic control has been attempted in individual color channels, overall balance between three color channels has not been successfully achieved in the past. Therefore, it is an object of this invention to provide an apparatus which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the pertinent art.
Another object of this invention is to provide an apparatus for displaying two-channel audio input signals in a three-color visual pattern formed by a moving spot wherein the apparatus comprises phase shifting means for phase shifting a first audio signal, first filtering means for filtering said first audio signal to produce a first filtered audio signal, second filtering means for filtering a second audio signal to produce a second filtered audio signal, means for controlling the position of the spot as a function of the first and second filtered audio signals, mixing means for mixing said first and second audio signals to produce a mixed audio signal, frequency discrimination means for dividing said mixed audio signal into a high frequency component, a mid-frequency component and a low frequency component, color balance means for controlling the amplitudes of the three frequency-discriminated audio signals, and color driver means driven by said frequency-discriminated audio signals for controlling the intensities of the three color components of the spot.
Another object of this invention is to provide an apparatus for displaying two-channel audio input signals in a three-color visual pattern, wherein said color balance means includes feedback means for summing the three frequency-discriminated audio signals to produce a color balance signal and first, second and third comparator means for controlling the amplitudes of said frequency-discriminated audio signals as a function of said color balance signal.
Another object of this invention is to provide an apparatus for displaying two-channel audio input signals in a three-color visual pattern, including first, second and third detector means for rectifying the outputs of the three frequency discrimination means.
Other objects and a fuller understanding of this invention may be had by referring to the summary of the invention, the description and the claims taken in conjunction with the accompanying drawings.